Systems that use liquids face the problem of separating gas or vapor from the liquid, or more particularly, of collecting the liquid at a specified location and collecting the gas or vapor at another specified location. Examples include fuel lines, coolant loops, hypodermic syringes, and materials processing. For most such systems operating on Earth, the dense liquid is easily separated from the less dense gas and collected at a preferred location by the force of gravity, provided that the system is properly oriented with respect to the gravity vector. However, for such systems operating in a low gravity environment, such as in orbiting spacecraft, the liquid is not necessarily aggregated at a known location in the tank. Instead, the liquid and gas mix freely throughout the volume of its container or conduit. Therefore, a need for orienting liquid with respect to a gas or vapor in a low gravity environment arises.
One method for effecting gas-liquid orientation in an orbiting spacecraft involves firing attitude thrusters to produce acceleration along a preferred axis. This method has drawbacks. In addition to increasing the operational complexity of a space mission, firing attitude thrusters also requires consumption of attitude propellant, a strictly limited resource.
Another method uses an elastic bladder to confine the liquid at one end of a rigid tank, with liquid on one side of an elastic membrane and gas or vapor on the other side. Use of an elastic bladder poses significant problems and concerns. First of all, leakage in the bladder may cause system failure. Secondly, the mass of the bladder and its mounting apparatus reduces the performance level of the system. Thirdly, the bladder must often contain costly materials that can maintain elasticity even after prolonged contact with the liquid, which may be corrosive. Fourthly, extensive testing on the materials is often required. Fifthly, the bladder cannot remove a gas or vapor bubble which forms inside the bladder.
Another method uses centripetal force from a rotating device to move the dense liquid radially outward and the less dense gas radially inward. Use of a centrifigal system poses significant concerns. The system requires one or more motors which consume power and generate vibration and noise. The system contains moving parts which present a risk of mechanical failure.
Another method uses a liquid acquisition device with a finely channeled surface made of a wettable material. The liquid acquisition device connects the interior of the container with an outlet port. This method is often used in rocket propellant tanks. It is based on the theory that capillary action will accumulate a sufficient amount of propellant at the outlet port to start the system, after which the rocket's acceleration will maintain the position of the liquid propellant at the outlet port. This method presents some concerns. This method sometimes fails for reasons that are poorly understood. In addition, the liquid acquisition device is complex to fabricate and adds substantial mass to the system.
Yet another method uses a magnet to attract a paramagnetic liquid, thereby moving the liquid to a desired location near the magnet and separating the liquid from a gas or vapor that is magnetically repelled or less strongly attracted. This method is only effective when used with paramagnetic liquids. However, the great majority of liquids are diamagnetic, not paramagnetic.
Accordingly, it is an object of this invention to provide a method and system for orienting diamagnetic liquids with respect to gas or vapor in a low gravity environment.
It is another object of this invention to provide a method and system for orienting diamagnetic liquids with respect to gas or vapor in a low gravity environment that is simple and inexpensive.
It is another object of this invention to provide a method and system for orienting diamagnetic liquids with respect to gas or vapor in a low gravity environment that is low in weight.
It is yet another object of this invention to provide a method and system for orienting diamagnetic liquids with respect to gas or vapor in a low gravity environment that does not leak.
It is yet another object of this invention to provide a method and system for orienting diamagnetic liquids with respect to gas or vapor in a low gravity environment that has low power consumption and has no moving parts.
It is yet another object of this invention to provide a method and system for orienting diamagnetic liquids with respect to gas or vapor in a low gravity environment that is reliable.